The truth of the matter is, we all come to prayer with a tangled mass of motives - altruistic and selfish, merciful and hateful, loving and bitter. Frankly, this side of eternity we will never unravel the good from the bad, the pure from the impure. But what I have come to see is that God is big enough to receive us with all our mixture. We do not have to be bright, or pure, or filled with faith, or anything. That is what grace means, and not only are we saved by grace, we live by it as well. And we pray by it.
Jesus reminds us that prayer is a little like children coming to their parents. Our children come to us with the craziest requests at times! Often we are grieved by the meanness and selfishness in their requests, but we would be all the more grieved if they never came to us even with their meanness and selfishness. We are simply glad that they do come - mixed motives and all. (Richard Foster, Prayer)